Posted
by
timothyon Friday July 10, 2009 @04:50AM
from the this-time-let's-go-sideways dept.

Boccaccio writes "NASA on Wednesday successfully tested its MLAS alternative launch escape system designed for the new Orion Crew module. MLAS, or Max Launch Abort System, is named after the inventor of the crew escape system on the Mercury program, Maxime (Max) Faget and consists of four rocket motors built into a fairing that encloses an Orion module during Launch. MLAS is designed to pull the crew away from the main rocket stack during the critical first 2.5 minutes of flight in the event of a catastrophic failure. The advantage of the MLAS system over the more traditional LAS (Launch Abort System) is that it reduces the total height of the rocket, lowering the center of gravity and adding stability, and potentially allowing higher fuel load.
You can watch a video of the launch at the NASA website, and there are also a bunch of pictures."

I just watched the video - and while it definitely is a cool concept, what immediately came
to mind is the increased complexity of the system. I counted five separations (the launch itself
would be a separation in reality) of some piece or another and multiple chute deployments before the
crew capsule was safely floating down on its main parachutes.

I'm sure there's redundancy in there so a single failure wouldn't be fatal (although not dropping the
casing preventing main chute deployment would be bad), but it is quite a step up from the regular
"separate, fire one solid booster, wait a bit, deploy chutes" apporach.

i concur, the first thing i thought watching the launch video was "damn, thats a lot of parachutes to potentially get fouled" it seems like a far to complex system for something that, if its needed, needs to perform flawlessly. (that said, one hopes to never need the damn thing)

I initially thought the same thing, but perhaps they need variable descent rates and perhaps the first set or two of chutes is more likely to get tangled, ripped, or burned. We also don't know if the failure of one system prevents all the subsequent systems from operating or not. It may be more reliable than it first appears.

after 2 minutes of bastoff this sucker would normally be pretty damn high. The first stages are pretty much just drag chutes to ensure correct orientation. The next few stages are used to slow it down to a safe speed and/or altitude to deploy the final much larger chutes that might not be able to withstand deployment at a high speed/altitude. Another reason may be that they want to get these guys down as quickly as possible. Thus the drag shoots for control, and a few stages of chutes to slow down/land without putting their heads through their stomachs.

Though any of the steps can go wrong, the likelihood of each going wrong also matters. I don't know the record of failed separations and parachute deployments well enough to really say, but both technologies pre-date manned space flight, and have been continuously necessary, so they might be down pat. If there's a very low rate for either or both, it might be safer than a system with fewer stages but more inherent danger for the crew. Depending on the odds, I might prefer five low-risk threats to three m

I just watched the video - and while it definitely is a cool concept, what immediately cameto mind is the increased complexity of the system

I guess the question is, what does the complexity buy them? Complexity for complexities sake is foolish, for sure, but if they get something useful out of the complexity,then it might be worth it. I wonder what the gain is they perceive to be getting, and how much its worth relative to the complexity.

I just watched the video - and while it definitely is a cool concept, what immediately came to mind is the increased complexity of the system. I counted five separations (the launch itself would be a separation in reality) of some piece or another and multiple chute deployments before the crew capsule was safely floating down on its main parachutes.

What the video and accompanying article doesn't make clear is that most of those separation events were part of the test vehicle, not part of the proposed flight

This system is only as complex as necessary. If it could be simplified, it would. Do you have any idea of how recovery of spacecraft components works, such as recovery of the solid rocket motors? The first parachutes, the small ones, help to slow down the capsule. These parachutes can withstand a certain amount of load. Do you know what dynamic pressure is and how it drives the aero forces in atmo? The next batch of parachutes can withstand another set of forces, and finally the huge babies are released whe

However when looking at the video there is the posibilty they get other elements of the escape capsule on their head after a succesful landing.

Also i am a bit subrised they do not escape sideways. In the final system they have a rocket under their feet that is pushing up. escaping in that direction might not be the safest direction if they already have altitude.

Being that it's straight up, and for only the first two and a half minutes, it's a fairly safe route to take. When there is a massive failure of the launch vehicle, it's doubtful that much of the debris will continue on it's original trajectory once failure (ie. explosion/incorrect separation) - Maybe the stress of continuing to be launched upward is considerably less than say, having an explosion, and going from thousands of miles an hour straight up, to instant jet to one side.. I'd rather eat scrambled e

However when looking at the video there is the posibilty they get other elements of the escape capsule on their head after a succesful landing.

I know this is/., but try RTFA:

Because the MLAS flight test vehicle was not optimized for weight and parachute performance, there may be recontact between the elements of the test vehicle after the parachutes are fully deployed and after all the required data is collected. If recontact does occur it will not affect the MLAS test objectives, nor will it apply to Orion -- as the MLAS design and hardware are not representative of the current Orion design.

This is from Carrying the Fire, by Michael Collins. The story as Collins tells it is that as the crew entered the capsule for the launch he noticed that Armstrong had a loose strap on the thigh of his pressure suit which was about to snare a T shaped hand controller. The launch escape system is triggered by twisting the controller so there was a risk of accidently triggering it. In the book he suggests the last word spoken in the CM before the LES fired would be "oops".

They shoulda ran with it. Awesome names and acronyms have come out of stranger places. For example, my Dad knows one of the engineers that built the San Diego Wild Animal park. They were trying to decide a name for the park's monorail, now known as Wgasa. Apparently, after they had been at it for days one of the engineers coworkers said "Who gives a shit anyway?":D The story has no official evidence to back it up, but Snopes still believes it to be true.

An enhancement is, to alwads add vowels of the original words in between consonants that are hard to spell,Wgasa, for example, would be more easy spelled, if it would have been called Wogasa or Whogasa.

I gather that's correct to stage 7. According to my dim understanding, past that you:

8. Hop in an armored van.
9. Peel out like you're Mad Max with a horde of post-apocalyptic, biker cannibals on your tail.
10. Huddle down in a nearby bunker about a mile or so away which can take anything short of a direct hit by an errant SRB.